U.S. patent number 3,944,636 [Application Number 05/577,426] was granted by the patent office on 1976-03-16 for cooling tower.
This patent grant is currently assigned to GEA Luftkuehlergesellschaft Happel GmbH & Co. KG. Invention is credited to Hans-Bernd Gerz, Franz J. Schuldenberg.
United States Patent |
3,944,636 |
Schuldenberg , et
al. |
March 16, 1976 |
Cooling tower
Abstract
A cooling tower has circumferentially distributed inlet openings
at the lower end for the entrance of cooling air and a central
upper outlet opening. Cooling air flows through the tower, on the
one hand, counter-currently to a medium to be cooled which flows in
downward direction over a trickling unit (wet cooling section), and
on the other hand, parallel thereto about heat-exchanger elements,
flown through by a medium to be cooled (dry cooling section). The
trickling unit and the heat-exchanger elements are separated from
each other.
Inventors: |
Schuldenberg; Franz J. (Bochum,
DT), Gerz; Hans-Bernd (Bochum, DT) |
Assignee: |
GEA Luftkuehlergesellschaft Happel
GmbH & Co. KG (Bochum, DT)
|
Family
ID: |
5915835 |
Appl.
No.: |
05/577,426 |
Filed: |
May 14, 1975 |
Foreign Application Priority Data
|
|
|
|
|
May 17, 1974 [DT] |
|
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2424059 |
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Current U.S.
Class: |
261/159; 165/900;
261/DIG.77; 165/129; 261/DIG.11; 261/109 |
Current CPC
Class: |
F28F
25/12 (20130101); F28C 1/14 (20130101); Y10S
261/77 (20130101); Y10S 261/11 (20130101); Y10S
165/90 (20130101); Y02B 30/70 (20130101) |
Current International
Class: |
F28C
1/14 (20060101); F28F 25/12 (20060101); F28F
25/00 (20060101); F28C 1/00 (20060101); F28C
001/06 (); F28D 005/00 () |
Field of
Search: |
;261/DIG.11,109,64R,158-161,111,DIG.77 ;165/129 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Miles; Tim R.
Assistant Examiner: Clements; Gregory N.
Attorney, Agent or Firm: Striker; Michael J.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims:
1. A cooling tower arrangement comprising a cooling tower having an
upper open end and a plurality of air inlet openings at the lower
end; a central cooling shaft coaxially arranged within the cooling
tower and defining between its outer surface and the inner surface
of the cooling tower an annular space, said cooling shaft having an
upper open end and a plurality of inlet openings at the lower end
thereof; a plurality of heat-exchanger elements to be flown through
by a medium to be cooled being arranged in said annular space in a
plurality of concentric rings and extending in each ring in
substantially radial direction and downwardly inclined toward said
central shaft with the radially outermost ends of the
heat-exchanger elements in the outermost ring located above said
air inlet openings in the tower and with the radially innermost
ends of the heat-exchanger elements of the innermost ring located
at the inlet openings of the shaft so that the plurality of said
heat-exchanger elements form a bowl-shaped arrangement in said
annular space curving downwardly towards said shaft; and a
trickling unit extending transverse through said central shaft in
the region of said inlet openings therein over which a medium to be
cooled is adapted to flow in downward direction so that cooling air
will flow in one stream countercurrently to the flow of the medium
to be cooled over said trickling unit and in an outer stream
parallel to said one stream over said heat-exchanger elements.
2. A cooling tower arrangement as defined in claim 1, wherein said
trickling unit is arranged at an elevation substantially equal to
that of the heat-exchanger elements in the innermost ring.
3. A cooling tower arrangement as defined in claim 1, and including
a ventilator rotatable about a vertical axis in said central
cooling shaft above said trickling unit therein.
4. A cooling tower arrangement as defined in claim 1, and including
at least two ventilators arranged rotatable about vertical axes in
said central cooling shaft above said trickling unit therein.
5. A cooling tower arrangement as defined in claim 1, wherein the
upper open end of said central cooling shaft is located at a higher
elevation than the air inlet openings of the cooling tower.
6. A cooling tower arrangement as defined in claim 1, wherein the
open cross-section of said central cooling shaft increases towards
the upper open end thereof.
7. A cooling tower arrangement as defined in claim 1, and including
air guide means in the region of the upper open end of said central
shaft for imparting to the stream of cooling air passing
therethrough an outwardly inclined direction to intimately mix the
moisture laden air emanating from said cooling shaft with the
substantially dry air passing upwardly through said annular
space.
8. A cooling tower arrangement as defined in claim 3, wherein said
central cooling shaft is provided in the region between said
trickling unit and said ventilator with openings, and including
louvres in said openings movable between an open and a closed
position.
9. A cooling tower arrangement as defined in claim 1, and including
louvres in said air inlet openings at the lower end of said central
cooling shaft movable between an open and a closed position.
10. A cooling tower arrangement as defined in claim 1, wherein the
median inner diameter of said central cooling shaft is about
one-third to one-sixth of the inner diameter of the tower in the
region of the air inlet openings of the latter.
11. A cooling tower arrangement as defined in claim 1, and
including a liquid collecting container at the bottom of said
central cooling shaft.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a cooling tower having
circumferentially distributed inlet openings at the lower end for
the entrance of cooling air and a central upper outlet opening,
through which cooling air flows, on the one hand, countercurrently
to a medium to be cooled with flows in downward direction over a
trickling unit (wet cooling section), and on the other hand,
parallel thereto about heat-exchanger elements, flown through by a
medium to be cooled (dry cooling section), and in which the
trickling unit and the heat-exchanger elements are separated from
each other.
In a known cooling tower construction of the aforementioned kind,
the wet cooling section and the dry cooling section are divided in
a plurality of V-shaped sectors, as considered in horizontal cross
section of the cooling tower, with the sectors of the wet cooling
section alternating with those of the dry cooling section in
circumferential direction of the tower. Separating walls between
the alternating, successive sectors of the wet cooling section and
the dry cooling section create passages, which diminish in cross
section toward the central axis of the tower, through which the
cooling air passes. Each sector of the wet cooling section is
provided with a radially extending main channel and with normally
thereto arranged auxiliary channels from which the medium to be
cooled, in this case water, flows through openings in the bottom of
the channels downwardly over trickling units in countercurrent to
the upwardly flowing cooling air. The radial main channels and the
normally arranged auxiliary channels extend nearly over the total
horizontal cross section of each V-shaped sector of the wet cooling
section. A collecting reservoir for the water is provided at the
bottom of these sectors.
The sectors for the dry cooling section have channels of
substantially open cross section which are only at the
circumference of the tower provided with substantially vertically
extending heat-exchanger elements. The updraft for the cooling air
for the wet cooling section as well as for the dry cooling section
is produced by a ventilator arranged above the aforementioned
sectors on a central column.
An essential disadvantage of this known construction consists in
that the heat-exchanger elements of the dry cooling section are
arranged on the circumference of the cooling tower. Such an
arrangement will be susceptible to the influence of wind passsing
around the cooling tower since during passing of wind around the
cooling tower a greatly varying pressure profile will be formed on
the circumference of the tower. The influence of the wind passing
around the cooling tower is further increased by the radial
separating walls between the sectors of the wet cooling section and
the dry cooling section. Such separating walls are, however,
absolutely necessary in this known cooling tower construction since
otherwise the cooling surfaces of the dry cooling section may be
wetted with contaminated water. In addition, the necessary radial
separating walls evidently increase the production costs of such a
cooling water considerably.
In this known construction it is also necessary to provide separate
air inlet openings for the sectors of the wet cooling section as
well as for the sectors of the dry cooling section. Such different
air inlet openings are difficult to realize constructively and this
is an additional considerable disadvantage of the known cooling
tower construction. Furthermore, due to the alternating arrangement
of sectors for the wet cooling section and sectors for the dry
cooling section, the arrangement of the necessary conduits,
especially for the dry cooling section, will be complicated and
expensive. In addition, the collecting container for the water to
be cooled in the wet cooling section will necessarily extend
substantially over the whole cross section of the cooling tower,
which likewise increases its production costs.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a cooling tower
with a wet cooling section and a dry cooling section which
overcomes the above described disadvantages of such cooling towers
known in the art.
It is a further object of the present invention to provide a
cooling tower of the aforementioned kind having a wet cooling
section and a dry cooling section over which the cooling air flows
in parallel streams, which can be manufactured at a considerably
lower cost than the above described cooling tower known in the
art.
It is a further object of the present invention to provide a
cooling tower of the aforementioned kind with an improved operating
characteristic and in which formation of vapor clouds emanating
from the tower is substantially prevented.
With these and other objects in view, which will become apparent as
the description proceeds, the cooling tower according to the
present invention having an upper open outlet end and a plurality
of air inlet openings at the lower end thereof, is provided with a
central cooling shaft coaxially arranged within the cooling tower
and defining between its outer surface and the inner surface of the
cooling tower an annular space in which a plurality of radially
extending heat-exchanger elements are provided in a plurality of
concentric rings in a substantially bowl-shaped arrangement
starting above the air inlet openings in the cooling tower and
gradually sloping downwardly toward the central cooling shaft,
whereas a trickling unit is arranged extending transverse through
the central shaft over which a medium to be cooled is adapted to
flow in downward direction so that cooling air will flow in one
stream countercurrently to the flow of the medium to be cooled over
the trickling unit and in an other stream parallel thereto over the
heat-exchanger elements.
The construction of the present invention has the advantage that no
heat-exchanger elements are provided directly at the circumference
of the cooling tower so that the greatly different pressure profile
around the cooling tower during passage of winds about the same
will have no influence on the performance of the heat-exchanger
elements. The cooling air can enter freely in radial direction
through the air inlet openings provided circumferentially at the
lower end of the cooling tower and the cooling air passes without
hindrance to the heat-exchanger elements arranged in the annular
space between the central cooling shaft and the tower as well as to
the inlet openings of the central cooling shaft. Thereby the
reduction of the cross section of the passage for the inflowing
cooling air beneath the bowl-shaped, toward the center of the
cooling tower inclined arrangement of the heat-exchanger elements
will be advantageous for the uniform impingement of cooling air
onto the heat-exchanger elements. Separating walls for separately
guiding the air to wet cooling sectors or dry cooling sectors
become unnecessary, which evidently considerably reduces the
production cost of the cooling tower according to the present
invention.
The central arrangement of the wet cooling shaft makes it also
possible to arrange the collecting container only in the central
cooling shaft below the trickling unit therein. This will likewise
reduce the production cost of the cooling tower. According to the
present invention, it is also possible to arrange the trickling
unit in the central cooling shaft at an optimium height. An
influence of the wet cooling section onto the dry section is
thereby avoided. The necessary support construction for the
trickling unit can be thereby reduced and in addition the height to
which the medium to be passed over the trickling unit has to be
pumped can likewise be lowered.
The heat-exchanger elements in the dry cooling section are
preferably roof shaped with conduits provided with cooling ribs.
The radial arrangement of the heat-exchanger elements in individual
concentric rings and the bowl-shaped, toward the central axis of
the cooling tower declining, arrangement of the rings will assure
an efficient use of the available room in the tower and therewith
an especially high efficiency.
Due to the concentric arrangement of the wet cooling section and
the dry cooling section, the moisture laden warm air from the wet
cooling section will be surrounded by a layer of dry warm air. This
will assure that formation of vapor clouds at the outlet end of the
cooling tower will be positively prevented, an advantage derivable
from cooling towers of the known art only during favorable weather
conditions, that is, at elevated outer temperatures and a
relatively low air humidity. Since in the arrangement according to
the present invention a greater volume of air passes through the
dry cooling section and this air passing through the dry cooling
section will surround the air passing through the wet cooling
section the formation of vapor clouds will be positively prevented
independent of the season.
An especially advantageous arrangement according to the present
invention is obtained by arranging the trickling unit in the
central cooling shaft at an elevation at which the inner, that is
the lowest heat-exchanger element ring is arranged. This will
assure an advantageous location of the trickling unit without
influencing the dry cooling section and which, as mentioned above,
reduces also the support construction for the trickling unit and
the height to which the medium to be cooled has to be pumped.
A further feature of the present invention consists of providing a
ventilator rotatable about a vertical axis above the trickling unit
in the central wet cooling shaft to thereby increase the updraft of
the air passing through the cooling tower. The additional
advantages derivable from such an arrangement is that the air
streams which pass upwardly through the wet cooling section and the
dry cooling section are intensively mixed with each other which
further reduces the possibility of any cloud formations at the
upper end of the cooling tower. The use of such a ventilator will
assure further that the dimension of the wet cooling section may be
reduced while producing the same cooling effect. The provision of a
ventilator will additionally provide for any desired regulation
during change of the heat load between the wet cooling section and
the dry cooling section.
The invention is, of course, not limited to the arrangement of a
single ventilator in the wet cooling shaft, but in accordance with
the use of the cooling tower it can be advantageous to provide two
or more ventilators rotating about vertical axes in the wet cooling
shaft.
According to a further feature of the present invention, the upper
outlet opening of the central wet cooling shaft is arranged above
the air inlet openings in the wall of the cooling tower. This will
further increase mixing of the warm air streams passing upwardly
through the wet cooling section and the dry cooling section. The
mixing of the dry air stream with the air stream saturated with
humidity is further improved by gradually increasing the
cross-section of the central wet cooling shaft toward the upper
outlet opening thereof. In this way, the wall of the outer cooling
tower and that of the wet cooling shaft are curved in opposite
directions to assure thereby that the air streams passing
therethrough will cross each other.
The intimate mixing of the warm air streams emanating from the wet
cooling section and the dry cooling section can be further improved
by providing air guide means in the region of the upper open end of
the cooling shaft for imparting to the stream of air passing
therethrough an outwardly curving movement.
Depending on the season of the year and also dependent on the
amount and the temperature of the medium to be cooled, whereby for
instance in the wet cooling section another medium may be cooled
than in the dry cooling section, it may be advantageous, in order
to obtain the best heat exchange effect, to vary the cooling effect
obtainable from the dry cooling section and the wet cooling
section. For this purpose, a plurality of openings which are
closeable by louvres are provided in a preferred arrangement
according to the present invention in the region between the
trickling unit and the ventilator or ventilators arranged above the
same and it is further advantageous to provide such louvres at the
inlet openings provided at the lower end of the central cooling
shaft so that these air inlet openings for the central cooling
shaft may be closed by such louvres.
During parallel operation of the wet cooling section and the dry
cooling section, the louvres in the region between the ventilator,
respectively ventilators, and the trickling unit are closed and the
louvres in the air inlet openings of the central shaft below the
trickling unit are opened. If the louvres at the air inlet opening
of the central shaft are closed and the louvres in the wall of the
central shaft between the trickling unit and the ventilator,
respectively the ventilators, are opened, then the cooling tower
may be operated strictly as dry cooling tower. By arranging the
elevation of the ventilator, or the ventilators, above the
trickling units, that is above at least the inner, i.e., the lowest
of the heat-exchanger element rings it is possible to expedite a
part of the already warmed-up air of the dry cooling section to
thus support the updraft of the warmed air. Of course during such
use, feeding of the medium to be cooled to the trickling unit has
to be interrupted. The warmed-up air located above the inner
heat-exchanger elements of the dry cooling section is drawn by the
ventilator or ventilators in part through the upper open louvres
into the central cooling shaft and thereby accelerated. Due to the
withdrawal of warm air from above the heat-exchanger elements, the
updraft of the total air stream is accelerated so that the flow of
air to the heat-exchanger elements is increased and the heat
exchange thus produced is considerably improved.
According to a further feature of the present invention, the median
diameter of the central shaft is about a third to a sixth of the
diameter of the cooling tower in the region of the air inlet
openings of the latter.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a partial cross-sectioned side view of the cooling tower
arrangement according to the present invention;
FIG. 2 is a horizontal cross-section through half of the cooling
tower taken along line II--II of FIG. 1, as viewed in the direction
of the arrow; and
FIG. 3 is a view similar to FIG. 1 and showing a modified
arrangement.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The cooling tower arrangement according to the present invention,
which is only schematically illustrated in FIGS. 1 and 2, comprises
a cooling tower 1 of known cross-section which is preferably
constructed from reinforced concrete. The cooling tower 1 is over a
major part of its height closed in circumferential direction and
provided only in the region of its lower end with a support
construction 2 which forms a plurality of air inlet openings 3 in
the wall 4 of the cooling tower through which cooling air may enter
in radial direction into the interior of the cooling tower. The
cooling air entering the cooling tower will be warmed up, as will
be pointed out in the following description, and passes in upward
direction through the cooling tower to leave the latter through an
upper central outlet opening 5.
Coaxially arranged with the longitudinal axis 6 of the cooling
tower is a central wet cooling shaft 7. The height of the shaft 7
is so dimensioned that its upper outlet opening 8 is arranged at a
level above the upper ends of the air inlet openings 3 provided in
the cooling tower.
The central shaft 7 may likewise be constructed from reinforced
concrete, but other material may also be used for its construction.
The wall 9 of the central shaft 7 is provided in the lower region
thereof with openings 10 which may be closed by louvres located at
this region. A trickling unit 12 of known, and therefore not
detailedly described, construction extends transversely through the
open cross-section of the central shaft 7 above the openings 10 and
the medium to be cooled is supplied by conduits, not shown, to
trickle downwardly over the trickling unit 12 in countercurrent
direction to the cooling air passing laterally through the openings
10 and upwardly through the central cooling shaft.
A ventilator 13 rotatable about a vertical axis is arranged
upwardly spaced from the trickling unit 12 and the outer diameter
of the ventilator is only slightly smaller than the inner diameter
of the central shaft 7 in the region at which the ventilator is
arranged.
The wall 9 of the shaft 7 is additionally provided with openings 14
in the region between the ventilator 13 and the trickling unit 12,
and louvres 15 are arranged also in the openings 14 so that the
latter may be closed if desired. In FIG. 1 the louvres 11 as well
as the louvres 15 are shown in open position. The louvres 11 as
well as the louvres 15 may be moved from the open to the closed
position by actuating means well known in the art and not
illustrated in the drawing in order not to complicate the drawing
unnecessarily.
The vertical cross-section of the central shaft 7 is dimensioned in
such a manner that it increases gradually towards the upper outlet
end thereof.
The heat-exchanger elements 16 of the dry cooling section of the
cooling tower arrangement are located in the annular space between
the wall 4 of the cooling tower and the central shaft 7. Each of
the heat-exchanger elements 16 is in substantially gable roof form
with the two sides of the cooling element formed by inclined
conduits provided with cooling ribs These conduits are at the head
and foot ends connected with each other by distributing,
respectively, collecting chambers. The cooling elements 16 are
substantially radially arranged in three concentric rings A, B and
C, and the conduits for feeding the medium to be cooled into the
cooling elements 16 are not shown in the drawing.
The three concentric rings A, B, C are mounted in a substantially
bowl-shaped, towards the central axis 6 inclined, arrangement. The
outer ends of the heat-exchanger elements 16 in the outer ring A
are thereby located above the inlet openings 3 for the cooling air
provided in the wall 4 of the cooling tower. The heat-exchanger
elements of the three rings are mounted on supports 17. The
conduits for feeding the medium to be cooled and for discharging
the medium from the heat-exchanger elements may be mounted on the
supports 17 and the conduit for feeding the medium to be cooled to
the upper ends of the heat-exchanger elements 16 of the outer ring
A may be supported on the wall 4 of the cooling tower. On the other
hand, the collecting chamber of the outermost ring A may be
directly connected to the distributing chamber of the
heat-exchanger elements in the ring B and the collecting chamber of
the latter may be connected to the distributing chamber of the
innermost ring C while the conduit for discharging the cooled
medium from the collecting chamber of the ring C would then be
supported on the innermost of the support 17. The cooling medium
discharged from the inner ring C may then be passed over the
trickling unit 12 in the central shaft 7, but on the other hand, it
is also possible to feed different mediums to be cooled through the
heat-exchanger elements 16 and over the trickling unit 12.
The above described cooling tower arrangement may be operated in
two different ways. By closing the louvres 15 in the central shaft
7 above the trickling unit 12, cooling air will pass upwardly
between the heat-exchanger elements 16 due to the natural draft
provided by the cooling tower and at the same time cooling air will
be forced upwardly through the trickling unit 12, when the louvres
11 are in the open position, by the ventilator 13 arranged above
the trickling unit 12 in the central shaft. On the other hand,
depending on the season of the year, respectively depending on the
amount and the temperature of the medium to be cooled, it is also
possible to close the louvres 11 located below the trickling unit
12 while keeping the louvres 15 above the trickling unit 12 in open
position so that only the dry section of the cooling tower will be
in operation. If during such operation the ventilator 13 is kept
running, then the warmed-up air above the heat-exchanger elements
is at least in the region of the inner ring C sucked partly through
the openings 14 by the ventilator 13 so that an accelerated updraft
of air and therewith improved heat exchange is obtained. Of course,
it is also possible to close or open the louvres 11 and 15 to a
varying degree to vary thereby the cooling effect provided by the
wet cooling section, respectively the dry cooling section, in any
desired manner.
It is also possible to provide the heat-exchanger elements 16 with
adjustable louvres to vary impingement of the cooling air on the
heat-exchanger elements in any desired manner.
A collecting container 18 for collecting the medium trickling
downwardly over the trickling unit 12 is provided at the bottom of
the central shaft 7 from which the cooling medium may be discharged
through a conduit, not shown in FIG. 1, in which a pump may be
arranged for pumping the cooled medium to any desired location.
FIG. 3 illustrates in a partly sectioned side view a modification
of the above described cooling tower arrangement.
The modification illustrated in FIG. 3 differs from the above
described arrangement in that two ventilators 13, rotatable about
vertical axes, are arranged in the central shaft 7. This central
shaft 7 is further provided at its upper outlet end with annular or
spirally arranged outwardly curving air guide vanes 20 so as to
deflect the air stream passing therebetween in outward direction as
indicated by the arrow b, so that the air stream forced upwardly by
the ventilators 13 through the central shaft will cross the air
stream passing in the direction as indicatd by the arrow c upwardly
in the annular space between the wall 4 of the cooling tower 1 and
the wall 9 of the central shaft 7, whereby the moisture laden air
stream passing through the central shaft 7 is thoroughly mixed with
the substantially dry air stream passing through the annular space
between the walls 4 and 9.
FIG. 3 also schematically illustrates the conduit 21 for
discharging the cooled medium from the collecting container 18 and
a pump 22 located in the conduit 21 for pumping the cooled medium
to any desired location.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of cooling tower arrangement differing from the types
described above.
While the invention has been illustrated and described as embodied
in a cooling tower arrangement provided with a central cooling
shaft, it is not intended to be limited to the details shown, since
various modifications and structural changes may be made without
departing in any way from the spirt of the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can, by applying current
knowledge, readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention.
* * * * *